net/netfilter/nf_conntrack_proto.c

   1 /* L3/L4 protocol support for nf_conntrack. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/mutex.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/stddef.h>
  20 #include <linux/err.h>
  21 #include <linux/percpu.h>
  22 #include <linux/notifier.h>
  23 #include <linux/kernel.h>
  24 #include <linux/netdevice.h>
  25
  26 #include <net/netfilter/nf_conntrack.h>
  27 #include <net/netfilter/nf_conntrack_l3proto.h>
  28 #include <net/netfilter/nf_conntrack_l4proto.h>
  29 #include <net/netfilter/nf_conntrack_core.h>
  30
  31 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[PF_MAX] __read_mostly;
  32 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX] __read_mostly;
  33 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  34
  35 static DEFINE_MUTEX(nf_ct_proto_mutex);
  36
  37 #ifdef CONFIG_SYSCTL
  38 static int
  39 nf_ct_register_sysctl(struct net *net,
  40                       struct ctl_table_header **header,
  41                       const char *path,
  42                       struct ctl_table *table)
  43 {
  44         if (*header == NULL) {
  45                 *header = register_net_sysctl(net, path, table);
  46                 if (*header == NULL)
  47                         return -ENOMEM;
  48         }
  49
  50         return 0;
  51 }
  52
  53 static void
  54 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  55                         struct ctl_table **table,
  56                         unsigned int users)
  57 {
  58         if (users > 0)
  59                 return;
  60
  61         unregister_net_sysctl_table(*header);
  62         kfree(*table);
  63         *header = NULL;
  64         *table = NULL;
  65 }
  66 #endif
  67
  68 struct nf_conntrack_l4proto *
  69 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  70 {
  71         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  72                 return &nf_conntrack_l4proto_generic;
  73
  74         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  75 }
  76 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  77
  78 /* this is guaranteed to always return a valid protocol helper, since
  79  * it falls back to generic_protocol */
  80 struct nf_conntrack_l3proto *
  81 nf_ct_l3proto_find_get(u_int16_t l3proto)
  82 {
  83         struct nf_conntrack_l3proto *p;
  84
  85         rcu_read_lock();
  86         p = __nf_ct_l3proto_find(l3proto);
  87         if (!try_module_get(p->me))
  88                 p = &nf_conntrack_l3proto_generic;
  89         rcu_read_unlock();
  90
  91         return p;
  92 }
  93 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
  94
  95 int
  96 nf_ct_l3proto_try_module_get(unsigned short l3proto)
  97 {
  98         int ret;
  99         struct nf_conntrack_l3proto *p;
 100
 101 retry:  p = nf_ct_l3proto_find_get(l3proto);
 102         if (p == &nf_conntrack_l3proto_generic) {
 103                 ret = request_module("nf_conntrack-%d", l3proto);
 104                 if (!ret)
 105                         goto retry;
 106
 107                 return -EPROTOTYPE;
 108         }
 109
 110         return 0;
 111 }
 112 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 113
 114 void nf_ct_l3proto_module_put(unsigned short l3proto)
 115 {
 116         struct nf_conntrack_l3proto *p;
 117
 118         /* rcu_read_lock not necessary since the caller holds a reference, but
 119          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
 120          */
 121         rcu_read_lock();
 122         p = __nf_ct_l3proto_find(l3proto);
 123         module_put(p->me);
 124         rcu_read_unlock();
 125 }
 126 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 127
 128 struct nf_conntrack_l4proto *
 129 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 130 {
 131         struct nf_conntrack_l4proto *p;
 132
 133         rcu_read_lock();
 134         p = __nf_ct_l4proto_find(l3num, l4num);
 135         if (!try_module_get(p->me))
 136                 p = &nf_conntrack_l4proto_generic;
 137         rcu_read_unlock();
 138
 139         return p;
 140 }
 141 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
 142
 143 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
 144 {
 145         module_put(p->me);
 146 }
 147 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
 148
 149 static int kill_l3proto(struct nf_conn *i, void *data)
 150 {
 151         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 152 }
 153
 154 static int kill_l4proto(struct nf_conn *i, void *data)
 155 {
 156         struct nf_conntrack_l4proto *l4proto;
 157         l4proto = (struct nf_conntrack_l4proto *)data;
 158         return nf_ct_protonum(i) == l4proto->l4proto &&
 159                nf_ct_l3num(i) == l4proto->l3proto;
 160 }
 161
 162 int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 163 {
 164         int ret = 0;
 165         struct nf_conntrack_l3proto *old;
 166
 167         if (proto->l3proto >= AF_MAX)
 168                 return -EBUSY;
 169
 170         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 171                 return -EINVAL;
 172
 173         mutex_lock(&nf_ct_proto_mutex);
 174         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 175                                         lockdep_is_held(&nf_ct_proto_mutex));
 176         if (old != &nf_conntrack_l3proto_generic) {
 177                 ret = -EBUSY;
 178                 goto out_unlock;
 179         }
 180
 181         if (proto->nlattr_tuple_size)
 182                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 183
 184         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 185
 186 out_unlock:
 187         mutex_unlock(&nf_ct_proto_mutex);
 188         return ret;
 189
 190 }
 191 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 192
 193 int nf_ct_l3proto_pernet_register(struct net *net,
 194                                   struct nf_conntrack_l3proto *proto)
 195 {
 196         int ret;
 197
 198         if (proto->init_net) {
 199                 ret = proto->init_net(net);
 200                 if (ret < 0)
 201                         return ret;
 202         }
 203
 204         return 0;
 205 }
 206 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
 207
 208 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 209 {
 210         BUG_ON(proto->l3proto >= AF_MAX);
 211
 212         mutex_lock(&nf_ct_proto_mutex);
 213         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 214                                          lockdep_is_held(&nf_ct_proto_mutex)
 215                                          ) != proto);
 216         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 217                            &nf_conntrack_l3proto_generic);
 218         mutex_unlock(&nf_ct_proto_mutex);
 219
 220         synchronize_rcu();
 221 }
 222 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 223
 224 void nf_ct_l3proto_pernet_unregister(struct net *net,
 225                                      struct nf_conntrack_l3proto *proto)
 226 {
 227         /* Remove all contrack entries for this protocol */
 228         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
 229 }
 230 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
 231
 232 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 233                                               struct nf_conntrack_l4proto *l4proto)
 234 {
 235         if (l4proto->get_net_proto) {
 236                 /* statically built-in protocols use static per-net */
 237                 return l4proto->get_net_proto(net);
 238         } else if (l4proto->net_id) {
 239                 /* ... and loadable protocols use dynamic per-net */
 240                 return net_generic(net, *l4proto->net_id);
 241         }
 242         return NULL;
 243 }
 244
 245 static
 246 int nf_ct_l4proto_register_sysctl(struct net *net,
 247                                   struct nf_proto_net *pn,
 248                                   struct nf_conntrack_l4proto *l4proto)
 249 {
 250         int err = 0;
 251
 252 #ifdef CONFIG_SYSCTL
 253         if (pn->ctl_table != NULL) {
 254                 err = nf_ct_register_sysctl(net,
 255                                             &pn->ctl_table_header,
 256                                             "net/netfilter",
 257                                             pn->ctl_table);
 258                 if (err < 0) {
 259                         if (!pn->users) {
 260                                 kfree(pn->ctl_table);
 261                                 pn->ctl_table = NULL;
 262                         }
 263                 }
 264         }
 265 #endif /* CONFIG_SYSCTL */
 266         return err;
 267 }
 268
 269 static
 270 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 271                                      struct nf_proto_net *pn,
 272                                      struct nf_conntrack_l4proto *l4proto)
 273 {
 274 #ifdef CONFIG_SYSCTL
 275         if (pn->ctl_table_header != NULL)
 276                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 277                                         &pn->ctl_table,
 278                                         pn->users);
 279 #endif /* CONFIG_SYSCTL */
 280 }
 281
 282 /* FIXME: Allow NULL functions and sub in pointers to generic for
 283    them. --RR */
 284 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 285 {
 286         int ret = 0;
 287
 288         if (l4proto->l3proto >= PF_MAX)
 289                 return -EBUSY;
 290
 291         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 292                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 293                 return -EINVAL;
 294
 295         mutex_lock(&nf_ct_proto_mutex);
 296         if (!nf_ct_protos[l4proto->l3proto]) {
 297                 /* l3proto may be loaded latter. */
 298                 struct nf_conntrack_l4proto __rcu **proto_array;
 299                 int i;
 300
 301                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 302                                       sizeof(struct nf_conntrack_l4proto *),
 303                                       GFP_KERNEL);
 304                 if (proto_array == NULL) {
 305                         ret = -ENOMEM;
 306                         goto out_unlock;
 307                 }
 308
 309                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 310                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
 311
 312                 /* Before making proto_array visible to lockless readers,
 313                  * we must make sure its content is committed to memory.
 314                  */
 315                 smp_wmb();
 316
 317                 nf_ct_protos[l4proto->l3proto] = proto_array;
 318         } else if (rcu_dereference_protected(
 319                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 320                         lockdep_is_held(&nf_ct_proto_mutex)
 321                         ) != &nf_conntrack_l4proto_generic) {
 322                 ret = -EBUSY;
 323                 goto out_unlock;
 324         }
 325
 326         l4proto->nla_size = 0;
 327         if (l4proto->nlattr_size)
 328                 l4proto->nla_size += l4proto->nlattr_size();
 329         if (l4proto->nlattr_tuple_size)
 330                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 331
 332         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 333                            l4proto);
 334 out_unlock:
 335         mutex_unlock(&nf_ct_proto_mutex);
 336         return ret;
 337 }
 338 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 339
 340 int nf_ct_l4proto_pernet_register(struct net *net,
 341                                   struct nf_conntrack_l4proto *l4proto)
 342 {
 343         int ret = 0;
 344         struct nf_proto_net *pn = NULL;
 345
 346         if (l4proto->init_net) {
 347                 ret = l4proto->init_net(net, l4proto->l3proto);
 348                 if (ret < 0)
 349                         goto out;
 350         }
 351
 352         pn = nf_ct_l4proto_net(net, l4proto);
 353         if (pn == NULL)
 354                 goto out;
 355
 356         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 357         if (ret < 0)
 358                 goto out;
 359
 360         pn->users++;
 361 out:
 362         return ret;
 363 }
 364 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 365
 366 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 367 {
 368         BUG_ON(l4proto->l3proto >= PF_MAX);
 369
 370         mutex_lock(&nf_ct_proto_mutex);
 371         BUG_ON(rcu_dereference_protected(
 372                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 373                         lockdep_is_held(&nf_ct_proto_mutex)
 374                         ) != l4proto);
 375         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 376                            &nf_conntrack_l4proto_generic);
 377         mutex_unlock(&nf_ct_proto_mutex);
 378
 379         synchronize_rcu();
 380 }
 381 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 382
 383 void nf_ct_l4proto_pernet_unregister(struct net *net,
 384                                      struct nf_conntrack_l4proto *l4proto)
 385 {
 386         struct nf_proto_net *pn = NULL;
 387
 388         pn = nf_ct_l4proto_net(net, l4proto);
 389         if (pn == NULL)
 390                 return;
 391
 392         pn->users--;
 393         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 394
 395         /* Remove all contrack entries for this protocol */
 396         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
 397 }
 398 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 399
 400 int nf_conntrack_proto_pernet_init(struct net *net)
 401 {
 402         int err;
 403         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 404                                         &nf_conntrack_l4proto_generic);
 405
 406         err = nf_conntrack_l4proto_generic.init_net(net,
 407                                         nf_conntrack_l4proto_generic.l3proto);
 408         if (err < 0)
 409                 return err;
 410         err = nf_ct_l4proto_register_sysctl(net,
 411                                             pn,
 412                                             &nf_conntrack_l4proto_generic);
 413         if (err < 0)
 414                 return err;
 415
 416         pn->users++;
 417         return 0;
 418 }
 419
 420 void nf_conntrack_proto_pernet_fini(struct net *net)
 421 {
 422         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 423                                         &nf_conntrack_l4proto_generic);
 424
 425         pn->users--;
 426         nf_ct_l4proto_unregister_sysctl(net,
 427                                         pn,
 428                                         &nf_conntrack_l4proto_generic);
 429 }
 430
 431 int nf_conntrack_proto_init(void)
 432 {
 433         unsigned int i;
 434         for (i = 0; i < AF_MAX; i++)
 435                 rcu_assign_pointer(nf_ct_l3protos[i],
 436                                    &nf_conntrack_l3proto_generic);
 437         return 0;
 438 }
 439
 440 void nf_conntrack_proto_fini(void)
 441 {
 442         unsigned int i;
 443         /* free l3proto protocol tables */
 444         for (i = 0; i < PF_MAX; i++)
 445                 kfree(nf_ct_protos[i]);
 446 }